5-nitrofuryl derivatives as antibacterial agents

ABSTRACT

Compounds of the class of 3-(5-nitro-2-furyl)-1H-pyrazolo(3,4d)pyrimidin-4(5H)-one have antibacterial properties and are active ingredients in pharmaceutical compositions and animal feedstuff compositions, an illustrative example is 1,6-dimethyl3-(5-nitro-2-furyl)-1H-pyrazolo(3,4-d)pyrimidin-4(5H)-one.

United States Patent [191 Hoyle et al.

[111 3,821,382 [4 June 28, 1974 [541 S-NITROFURYL DERIVATIVES AsANTIBACTERIAL AGENTS [75] Inventors: William Hoyle; Graham Arton YHowarth, both of Cheshire, England [73] Assignee: Ciba-GeigyCorporation, Ardsley,

[22] Filed: Aug. 23, 1972 [21] Appl. No.: 283,134

Related US. Application Data [62] Division of Ser. No. 84,531, Oct. 27,1970.

[30] Foreign Application Priority Data Oct. 28, 1969 Great Britain 52663/69 [52] U.S. C1. 424/251 [51] Int. Cl A6lk 27/00 [58] Field of Search424/251, 84, 531

[56] References Cited UNITED STATES [PATENTS 3,211,731 10/1965 Schmidtet al 260/2564 3,335,141 8/1967 Burch 260/2564 3,350,397 10/1967 Burch260/2475 Primary Examiner-Jerome D. Goldberg Attorney, Agent, orFirm-Joseph G. Kolodny; Ronald A. Daignault 2 Claims, No DrawingsDETAILED DESCRIPTION The present invention relates'to nitrofurylderivatives, in particular, to derivatives of 3-(5-nitro-2-furyl)- ll-l-pyrazolo[ 3,4,-d]pyrimidin-4( SI-U-one which compounds haveantibacterial properties. It further relates to pharmaceutical andanimal feedstuff compositions containing these compounds and to methodsfor the treatment of mammals suffering from bacterial infections,particularly of urinary tract infections, comprising administering tosaid mammals an effective amount of such compound. The invention alsoprovides methods for protecting organic material susceptible tobacterial attack with an effective amount of a compound according to theinvention.

More particularly, the present invention relates to compounds of theformula I wherein R, is alkyl having from one to fivecarbon atoms orcarbalkoxy having from one to five carbon atoms in the alkyl moiety, and

R is hydrogen, alkyl having from one to five carbon atoms which may beunsubstituted or substituted partially or completely by chloro or bromo;cycloalkyl having from five to seven carbon atoms in the carbocyclicring, aralkyl having up to 12 carbon atoms, or alkenyl having from twoto four carbon atoms. Examples of alkyl groups having from one to fivecarbon atoms are methyl, ethyl, n-propyl, isopropyl, nbutyl,tertiarybutyl, and n-pentyl groups. Preferably, R,

as an alkyl group contains from one to three carbon atoms. Cycloalkyl offrom five to seven carbon atoms embraces cyclopentyl, cyclohexyl andcycloheptyl groups, whereby the cyclohexyl group is preferred. By theterm aralkyl is meant for example the benzyl group and other groupsconsisting of an aryl and an alkyl moiety, such as phenylethyl,naphthylmethyl and the like. Alkenyl containing from two to four carbonatoms embraces the vinyl, ally], 2-methallyl, but 2-enyl and but- 3-enylgroup.

Compounds of formula I are produced by treating a compound of theformula II B (II) in which R, has the meaning as given under formula I,with a reagent R 'C(OR where R, is an alkyl group containing from one tothree carbon atoms, with or 5 without a reaction promotor such as acarboxylic acid anhydride, to give an intermediate of formula III 1 (IIIwherein R R and R are as herein before defined, which is cyclisedwithout isolation.

This reaction may be carried out directly between the compound II andthe selected reagent, or may be carried out in the presence of aninezrtsolvent, such as for example dimethylsulphoxide or dimethylformamide.The presence of an inert solvent is of course desirable if the compoundII is a solid. In all cases, the reaction willpreferably be carried outat a temperature of from C. to the reflux temperature of the reactionmixture. Alternatively, a compound of the general formula II Y may bereacted with a carboxylic acid derivative R COX or (R CO) O where R isas previously defined and X is hydroxyl, halogen (preferably chlorine orbromine), amino, or the grouping -OR where R is an alkyl or alkenylgroup containing from one to three carbon atoms, to give an intermediateof formula IV ll il wherein R and R are as previously defined. Thecompounds of formula IV are cyclised without isolation.

In a further process, compounds of general formula wherein R is asherein defined, may be reacted with fonnic acid or with carboxylic acidderivative R COX or (R CO) O, where R R and X have their previoussignificance [except that X may not be hydroxyl] to give an intermediateof general formula VI the reaction being carried out in the presence ofan acid or basic catalyst and the intermediate then isolated orimmediately cyclised without isolation. Compounds of general formula VIare novel per se, and have antimicrobial activity.

The starting compounds of formula Il can be prepared by hydrolysing thecorresponding nitrofurylpyrazole derivative having the formulae Vwherein R has the previous significance. The compounds of formula V arethemselves prepared by reacting the corresponding nitrofuryl-nitriliminewhich in one of its canonical forms may be represented by the formula Xwith malononitrile, where R, has its previous significance.

The nitrofuryl-nitrilimine of the formula X may conveniently begenerated, as required, during the course of the reaction withmalomonitrile, by treating with a base the correspondingnitrofuryl-a-halo-hydrazone having the formula Xl OzNl fl-0-halogen O lTheir antibacterial activity is demonstrated in a number of conventionalpharmacological tests. Thus it is shown that, for example, l-methyl-3-(5-nitro-2-furyl)- 1H-pyrazolo[3,4-d]pyrimidin-4(5l-l)-one and 1,6-dimethyl-3-(5-nitro-2-furyl)-1H-pyrazolo[3 ,4- d]pyrimidin-4(5H)-onehave in vitro an excellent growth inhibiting effect againststaphylococcus aureus, Escherichia coli, Klebsiella pneumonia,Salmonella typhi and others if added in amounts of about 1 to about 10y/ml to the bacterial culture.

The toxicity of the compounds of the invention as demonstrated forexample in mice is of favourable low order.

For their intended internal use, for example for the treatment ofintestinal and urinary tract infections, the active compounds areadministered in dosages depending on the kind of infection, the speciesand the age, weight and particular condition of the individual beingtreated. In general the daily dosage upon oral application will varyfrom about 1 to 100 mg/kg for mammals. The compounds may also be used toprotect a high molecular weight hydrophobic or other organic materialsusceptible to bacterial detenoniation by contacting the organicmaterial with, impregnating in or otherwise treating with, the compoundsin amounts up to about 5% by weight. The compounds also find applicationas growth-promoting additives to animal feedstuffs, to which they may beadded in proportion of from 5 to 500 parts per million.

Accordingly, the invention also provides a pharmaceutical compositioncomprising an antibacterially effective proportion of an active compoundof the invention and a pharmacologically acceptable solid carrier orliquid diluent.

The pharmaceutical compositions according to the invention contain atleast one active compound of the invention as active substance togetherwith a conventional pharmaceutical carrier. The type of carrier actuallyused depends to a great extent on the intended application; for externaluse, for example in disinfecting healthy skin, disinfecting wounds andin treating dermatoses and affections of the mucous membranes caused bybacteria, ointments, powders and tinctures are used in particular. Theointment bases may be anhydrous, for instance they can consist ofmixtures of wool fat and soft paraffin, or they can consist of aqueousemulsions in which the active substance is suspended. Suitable carriersfor powders are, for instance, rice starch and other starches; the bulkweight of the carriers may be made lighter, if desired, for example byadding highly dispersed silicic acid, or may be made heavier by addingtalcum. The tinctures may contain at least one active ingredient inaqueous ethanol, in particular 45% to ethanol, to which 10% to 20% ofglycerol may be added, if desired. Solutions prepared from polyethyleneglycol and other conventional solubility promoters, and also,optionally, from emulsifying agents, maybe used with particularadvantage in disinfecting healthy skin. The content of active ingredientin pharmaceutical compositions for external application is preferably inthe range of from 0.1% to 5%.

Gargles or concentrates for their preparation, and tablets for slowdissolution in the mouth, are suitable for the disinfection of the mouthand throat. The former are preferably prepared from alcoholic solutionscontaining 1% to 5% of active substance to which glycerol or flavouringsmay be added. Lozenges, that is solid dosage units, preferably have arelatively high content of sugar or similar substances and a relativelylow content of active substance, for instance 0.2% to 20% by weight, aswell as the usual convential additives such as binding agents andflavourings.

Solid dosage units, in particular tablets, dragees (sugar coatedtablets) and capsules, are convenient for use in intestinal disinfectionand for the oral treatment of urinary tract infections. These unitspreferably contain from to 90% of the active compound to enable theadministration of daily doses of from 0.1 to 2.5 grams to adults, or ofsuitable reduced doses to children to be made. Tablets and dragee coresare produced by combining the active compounds with solid, pulverulentcarriers such as lactose, saccharose, sorbitol, maize starch, potatostarch or amylopectin, cellulose derivatives or gelatines, preferablywith the addition of lubricants such as magnesium or calcium stearate orpolyethylene" glycols of suitable molecular weight. Dragee cores maythen be coated, for example with concentrated sugar solutions which canalso contain gum arabic, talcum and/or titanium dioxide, or they may becoated with a lacquer dissolved in volatile organic solvents or mixtureof solvents. Dyestuffs can be added to these coatings, for instance todifferentiate between varying dosages. Soft gelatine capsules and otherclosed capsules consist, for example, of a mixture of gelatines andglycerol and may contain, for example, mixtures of the active compoundwith polyethylene glycol. Hard gelatine capsules contain, for example,granulates of an active substance with solid pulverulent carriers, forinstance lactose, saccharose, sorbitol, mannitol, starches (such aspotato starch, maize starch or amylopectin), cellulose derivatives of.gelatines, and magnesium stearate or stearic acid.

In all forms for administration the active compounds can be present assolo active ingredients or they can also be combined with other knownpharmacologically active, and especially antibacterial and/orantimycotically active substances, for example to broaden the range ofapplication. They can be combined for example, with 5,7-dichloro-2-methyl-S-quinolinol or other derivatives of 8-quinolinol,with sulfamerazine or sulfafurazole or other derivatives ofsulfanilamide, with chloramphenicol or tetracycline or otherantibiotics, with 3,4,5-tribromosalicylanilide or other halogenatedsalicylanilides, with halogenated carbanilides, with halogenatedbenzoxazoles or benzoxazolones, withpolychloro-hydroxy-diphenylmethanes, with halogendihydroxy-diphenylsulphides, with 4,4'-dichloro-2- hydroxydiphenylether or 2 ',4,4'-trichloro-2-hydroxydiphenylether or otherpolyhalogenhydroxydiphenylethers, or with bactericidal quaternarycompounds or with certain dithiocarbamic acid derivatives such astetramethylthiuram disulphide. Also, carriers which themselves havefavourable pharmacological properties may be used, for instance sulphuras a powder base or zine stearate as a component of ointment bases.

The invention also provides a method of protecting an organic materialsusceptible to bacterial attack EXAMPLE 1 A mixture of 10 grams of5-amino-4-cyano- 1 -methyl- 3-(5-nitro'2-furyl)-pyrazole and 100millilitres of 90% formic acid was heated under reflux for 1 hour andcooled. The crystalline solid was collected, washed with water andrecrystallised from dimethylformamide. The product was1-methyl-3-(5-nitro-2-furyl)-lH- pyrazol0[3,4-d]pyrimidin-4(5l-l)-one,having melting point 300 C.

EXAMPLE 2 The procedure described in Example 1 was carried out using5-amino-4-carbamoyl- 1 ,-methyl -3-( 5-nitro-2- furyl)-pyrazole asstarting material instead of S-amino- 4-cyanol -methyl-3-( 5-nitro-2-furyl )-pyrazole, the reaction conditions being the same,

The product was l-methyl-3-(5-nitro2-furyl)-lH-pyrazolo[3,4-d]pyrimidin-4(5l-ll)-one, having melting which comprisestreating the material with an active compound of the invention. Theorganic material may be, for instance, a natural or synthetic polymericmaterial, a proteinaceous or carbohydrate substance, or a natural orsynthetic fibre or textile material formed therefrom.

point 300 C., identical with the product obtained in Example l.

EXAMPLE 3 EXAMPLE 4 The procedure described in Example 1 was carried outusing 5-amino-4-cyanol -isopropyl-3-( 5-nitro-2- furyl)-pyrazole asstarting material instead of 5-amino- 4-cyanol -methyl-3-(5-nitro-2furyl )-pyrazole, the reaction conditions being the same.

The product was l-isopropyl-3-((5-nitro-2-furyl)-lH-pyrazolo[3,4-d]pyrimidin-4(5H)-one.

EXAMPLE 5 The procedure described in Example 1 was carried out using5-amino-4-cyano-3-( 5-nitro-2-furyl)- l -npentyl-pyrazole as startingmaterial instead of S-amino- 4-cyanol-methyl-3-( 5-nitro-2-furyl)-pyrazole, the reaction conditions being the same.

The product was 3-(5-nitro-2-furyl)-l-n-pentyl-lH- pyrazolo[ 3 ,4-d]pyrimidin-4( 5H )-o ne.

EXAMPLE 6 A mixture of 10 grams of5-amino-4-carbamoyllmethyl-3-(5-nitro-2-furyl)-pyrazole and millilitresof acetic anhydride was heated under reflux for 6 hours and cooled. Thecrystalline solid was collected, washed with alcohol and recrystallisedfrom dimethylformamide.

EXAMPLE 7 The procedure described in Example 6 was carried out usingcrotonic anhydride as starting material instead of acetic anhydride, thereaction conditions being the same.

The product was 1-methyl-6-(1-propenyl)-3-(5- nitro-2-furyl l H-pyrazolo3,4-d1pyrimidin-4- (H)-one, which has melting point 300 C.

EXAMPLE 8 The procedure described in Example 6 was carried outusingchloro-acetic anhydride as starting material instead of aceticanhydride, the reaction conditions being the same.

The product was 6-chloromethyl-1-methyl-3-(5- nitro-2-furyl 1H-pyrazolo[ 3 ,4-d]pyrimidin-4 (5l-l)-one, which has melting point 300C. with decomposition.

EXAMPLE 9,

The procedure described in Example 6 was carried out using cyclohexanecarboxylic anhydride as staring material instead of acetic anhydride,the reaction conditions being the same.

The product was 6-cyclohexyll-methyl-3-(5-nitro-2- furyl l H-pyrazolo[ 3,4-d]pyrimidin-4-( 5 H )-one, which has melting point 300 C.

EXAMPLE 10 The procedure described in Example 6 was carried out usingphenylacetic anhydride as starting material instead of acetic anhydride,the reaction conditions being the same.

The product was 6-benzyl-l-methyl-3-(5-nitro-2- furyl)-1 H-pyrazolo[3,4-d pyrimidin-4( 5 H )-one, which has melting point 300 C.

EXAMPLE 1 1 EXAMPLE 12 The procedure described in Example 1 1 wascarried out using crotonic anhydride as starting material instead ofpropionic anhydride, the reaction conditions being the same.

The product was 1-methyl-3-(5-nitro-2-furyl)-6-(1- propenyl)-1H-pyrazolo[3,4-d]pyrimidin- (5 H)-one, having melting point 300C.

EXAMPLE 13 The procedure described in Example 1 1 was carried out usingbutyric anhydride as starting material instead of propionic anhydride,the reaction conditions being the same.

The product was l-methy1-3-(5-nitro-2-furyl)-6-propyl-1l-l-pyrazolo[3,4-d]pyrimidin-4(5H)-one, having melting point 300C.

EXAMPLE 14 A mixture of 14.0 grams of5-amino-4-cyano-lmethyl-3-(5-nitro-2-furyl)-pyrazole, 9.5 gramsisobutyric anhydride and 0.6 grams of concentrated sulphuric acid (8.6.1.84) was heated at a reaction temperature of l00120 C. for 15 minutesand then cooled. The solid which crystallised was collected, washed withether and dried. Recrystallisation from aqueous dimethylformamide gave4-cyano-5- isobutyramido- 1 -methyl-3-( 5 -nitro-2-furyl )-pyrazolehaving melting point 225 C. r

A mixture of 3.5 grams of 4-cyano-5-isobutyr-amido-1-methyl-3-(5-nitro-2-furyl)-pyrazole, 20 millilitres ofdimethylformamide and 10 millilitres of concentrated sulphuric acid (SC.1.84) was heated under relfux for 1 hour and cooled. The mixture wasthen diluted with 50 millilitres of water and the solid which formed wascollected, washed with water and dried. Recrystallisation fromdimethylformamide gave 6-isopropyl-1- methyl-3-( 5-nitro-2-furyl 1l-l-pyrazolo[ 3 ,4- d]pyrimidin-4(5l-l)-one, having melting point 300 C.

EXAMPLE 15 EXAMPLE 16 The procedure described in Example 1 1 was carriedout using chloroacetic anhydride as starting material instead ofpropionic anhydride, the reaction conditions being otherwise essentiallythe same. The product was6-chloromethyl-l-methyl-3-(5-nitro-2-furyl)-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one, having melting point 300 C. withdecomposition.

EXAMPLE 17 A mixture of 2.3 grams of 5-amino-4-cyano-l-.

methyl-3-(5-nitro-2-furyl)-pyrazole, 15 millilitres ofdimethylformamide, 15 millilitres of anhydrous pyridine and 0.8 grams ofacetyl chloride was heated under reflux for 2 hours and cooled. Themixture was diluted with 50 millilitres of ice-water and the solid whichprecipitated was collected, washed with water and dried.Recrystallisation from aqueous dimethylformamide gave5-acetamido-4-cyanol -methyl-3-( 5 nitro-2- furyl)-pyrazole havingmelting point 250 C.

EXAMPLE 18 a. The procedure described in Example 17 was caracid gave6-cyclohexyl-l-methyl-3-(5-nitro-2-furyl)-"1l-l-pyrazolo[3,4-d]pyrimidin-4(4H)-one, having melting point 300 C.

EXAMPLE 19 A mixture of 11.6 grams of-amino-4-cyano-lmethyl-3-(S-nitro-Z-furyl)-pyrazole, 7.7 grams ofphenylacetyl chloride, 50 millilitres of dimethylformamide and 30millilitres of anhydrous pyridine was heated under reflux for 4 hoursand cooled. The mixture was then diluted with 100 millilitres ofice-water and a crude solid was obtained. A mixture of this solid withmillilitres of dimethylforrnamide and 10 millilitres of concentratedsulphuric acid (8.0. 1.84) was heated under reflux for 30 minutes andcooled. Dilution of the mixture with 50 millilitres of ice-water yieldeda product which on recrystallisation from di' methylformamide gave6-benzyl-l-methyl-3-(5-nitro 2-furyl)- l H-pyrazolo-[3,4-d]pyrimidin-4-(5l-l)-one, having melting point 300 C.

EXAMPLE 20 The procedure described in Example 15 was carried out using5-amino-4-cyano-l-n-propyl-3-(5-nitro-2- furyl)-pyrazole as startingmaterial instead of S-amino- 4-cyano- 1 -ethoxycarbonyl-3-(5-nitro-2-furyl pyrazole.

The product was 6-methyl-1-n-propyl-3-(5-nitro-2- furyl l H-pyrazole[3,4-d]pyrimidin-4(5H )-one, having melting point 276 C.

EXAMPLE 2] PREPARATION OF TABLETS substance. If desired, the tablets canbe grooved for better adaption of the dosage.

Example 22 Preparation of Dragees for 1,000 Composition dragees l1,6-Dimethyl-3-(5- nitroZ-furyD-IH- pyrazolo[3,4-d]pyrimidin- 4(5H)-one100.0 g

Maize starch 27.0 g

Gelatin 8.0 g

ll Glycerol 2.0 g

Distilled water q.s. ad 100 ml Maize starch 10.0 g 111 Talcu'm I V 7.0 g

Magnesium stearate 1.0 g 155.0 g N White dragee coating Shellac 2.0 g

Sugar 50.0 g Talcum 38.0 g Gum arabic 7.4 g

Colloidal silicon dioxide 22 g Titanium dioxide 0.4 g

Composition I is granulated in the heat with composition I through asieve of 1.2 mmmesh diameter. The

dried granulate is mixed'with composition 11] and the resulting mixtureis pressed into 1,000 dragee cores. These are then coated withcomposition IV and dried. The dragees obtained weigh 255.0 mg andcontain 100 mg of active substance.

EXAMPLE 23 0 Preparation of a Syrup l-Methyl-3-(5-nitro-2-furyl)-1H-pyrazolo[3,4-d]pyrimidin-4( 5H )-one Colloidal silicone dioxidep-Hydroxybenzoic acid methyl ester p-Hydroxybenzoic acid propyl esterCitric acid Sodium cyclamate Distilled water Glycerol Sodiumcarboxymethyl cellulose Sugar The active substance and the colloidalsilicon dioxide are passed through a sieve of 1.2 mm mesh diameter (1).1

The p-hydroxybenzoic acid esters, the citric acid and the sodiumcyclarnate are dissolved in the given amount of boiling distilled water,the glycerol is then added to this solution (II). The sodiumcarboxymethyl cellulose and the sugar are thoroughly mixed (Ill).

Composition III is then added at C to Solution 11 under stirring untilcomplete dissolution of Ill. The viscous, slightly turbid liquid iscooled to room temperawherein R, is alkyl having from one to five carbonatoms or carbalkoxy having from one to five carbon atoms in the alkylmoiety; and R is hydrogen, alkyl having from one to five carbon atomswhich may be unsubstituted or substituted by chloro or bromo, cycloalkylhaving from five to seven carbon atoms in the carbocyclic ring, benzyl,phenylethyl, naphthylmethyl, or alkenyl having from two to four carbonatoms and an inert pharmaceutical carrier. 2. A method for the treatmentof a mammal suffering from a bacterial infection, which method comprisesadministering to said mammal an antibacterially effective amount of acompound according to claim 1.

2. A method for the treatment of a mammal suffering from a bacterialinfection, which method comprises administering to said mammal anantibacterially effective amount of a compound according to claim 1.